WO 2005/088675 discloses a high-pressure discharge lamp with a ceramic discharge vessel, which has a metal halide fill, the metal halides NaI, TlI, CaI2 and REI3 being used besides Hg and Xe. Primarily Ce, Nd and/or Pr are employed as rare earth metals RE. The wall load should be at least 30 W/cm2, expressed in terms of the region of the discharge length between the electrodes. This lamp is intended for automobile applications and is operated without acoustic resonance.
A similar high-pressure discharge lamp is presented in EP 1 729 324. Here, the possibility of resonant operation with longitudinal acoustic resonance is described in detail.